Application of Transmetalation to the Synthesis of Planar Chiral and Chiral-at-Metal Iridacycles
作者:Ross A. Arthurs、David L. Hughes、Peter N. Horton、Simon J. Coles、Christopher J. Richards
DOI:10.1021/acs.organomet.8b00905
日期:2019.3.11
chloride-substituted half-sandwich iridacycle as exclusively a single diastereoisomer. By reversing the lithiation diastereoselectivity by use of a deuterium blocking group, an alternative (S,Rp,SIr)-configured iridacycle was synthesized similarly. Use of (R)-Ugi’s amine as substrate in the lithiation/double transmetalation sequence gave an (R,Sp,SIr)-configured half-sandwich iridacycle, complexes of this
(S)-2-二茂铁基-4-(1-甲基乙基)恶唑啉的非对映选择性锂化,然后加入HgCl 2,通过(S,S p)-构型的汞取代配合物的重金属化形成。向其添加[Cp * IrCl 2 ] 2和四丁基氯化铵导致第二次金属转移反应,并形成(S,S p,R Ir)-构型的氯化物取代的半夹心iridacycle作为唯一的非对映异构体。通过使用氘保护基团逆转锂非对映选择性,另一种方法(S,类似地合成了R p,S Ir)-构型的iridacycle。在锂化/双金属转移序列中使用(R)-Ugi's胺作为底物可得到(R,S p,S Ir)-构型的半三明治式iridacycle,这种类型的配合物以前无法通过直接环氧化作用获得。从(S,S p)构型的Au(I)二茂铁基恶唑啉衍生物的合成也证明了锂到金的金属转移。(S,R p,S Ir)-iridacycle作为通过共沸HCO 2 H / NEt 3的还原胺化反应形成手性产物的催化剂,得到外消旋物。